Yes all 12 cards are running simultaneously.
The 12 risers are identical: https://www.amazon.es/gp/product/B073TFFWM9/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1

I checked a single slow card on another computer and also got 22MHs.

Motherboard: ASUS B250 Mining Expert
CPU: Intel Pentium G4400
RAM: 2x Crucial 4GB DDR4
HDD: Kingston SSD UV400 120Gb
Risers: Ptsaying 6 pin PCIe (link above)
PSU: 2x EVGA Supernova P2 1200W
OS: Windows 10 Pro